Method of producing polyarylene sulfide

ABSTRACT

The production method of the present invention includes: a supplying step of supplying reaction raw materials to at least one of a plurality of reaction vessels mutually communicated through a gas phase; a polymerizing step of carrying out a polymerization reaction; and a step of removing at least some of the water present in the reaction vessels. Each of the steps is carried out in parallel, and a reaction mixture is transferred sequentially between the reaction vessels. The total amount of water contained in the reaction raw materials in at least one of the reaction vessels to which the reaction raw materials are supplied is 3 moles or more per mole of the sulfur source, and the internal temperature of at least one of the reaction vessels to which the reaction raw materials are supplied is from 180° C. to 300° C.

TECHNICAL FIELD

The present invention relates to a polyarylene sulfide productionmethod.

BACKGROUND ART

Polyarylene sulfide (hereinafter, also referred to as “PAS”),represented by polyphenylene sulfide (hereinafter, also referred to as“PPS”), is an engineering plastic excelling in heat resistance, chemicalresistance, flame retardancy, mechanical strength, electricalcharacteristics, dimensional stability, and the like. PAS can be formedinto various molded products, films, sheets, fibers, and the like byordinary melt processing methods such as extrusion molding, injectionmolding, and compression molding. Therefore, PAS has been generally usedin a wide range of technical fields such as electrical devices,electronic devices, devices for automobiles, and packaging materials.

A method for producing PAS is disclosed in Patent Document 1.

Patent Documents 2 to 4 disclose PAS continuous polymerization devicesin which pressure-resistant polymerization vessels are connected inseries, and reaction solutions are transferred between eachpolymerization vessel using a difference in pressure, and also disclosemethods for continuous polymerization of PAS using the devices thereof.

In addition, Patent Document 5 discloses a method for producingsulfur-containing polymers, the method including the steps of (a)preparing in a first reaction vessel a mixture containing a sulfide anda solvent, and (b) reacting an aromatic dihalogen compound and thesulfide in a second reaction vessel to form a sulfur-containing polymer.

CITATION LIST Patent Literature

-   Patent Document 1: Japanese Examined Patent Application Publication    No. S45-3368A-   Patent Document 2: U.S. Pat. No. 4,056,515B-   Patent Document 3: U.S. Pat. No. 4,060,520B-   Patent Document 4: U.S. Pat. No. 4,066,632B-   Patent Document 5: Japanese Unexamined Patent Application    Publication (Translation of PCT Application) No. 2002-505361

SUMMARY OF INVENTION Technical Problem

Ordinarily, it is thought that polymerizing PAS in a short period oftime is difficult. The reason for this is that (i) PAS polymerization isa nucleophilic substitution reaction, and therefore the amount of waterthat is contained in the raw materials that are used when carrying outpolymerization in a short period of time is preferably small, butmonomer sulfur sources that can be ordinarily procured contain water,and therefore a step for reducing the amount of water content prior tothe polymerization reaction becomes necessary, and furthermore, (ii)during the polymerizing step, the sulfur source is present in a state ofbeing reacted and bonded with water, but the water is released inassociation with the consumption of the sulfur source through theprogression of polymerization, and this released water hinders thenucleophilic substitution reaction, and polymerization is therebyretarded.

As described above, conventional methods require a step of dehydratingin advance the raw materials containing water before carrying out thepolymerization reaction.

Patent Document 5 discloses a technique in which a mixture obtained byreacting the sulfur source and a solvent in the first reaction vessel isreacted in a second reaction vessel with p-dichlorobenzene, anddehydration of the hydrated water of the sulfur source is carried outduring that reaction. However, a problem with this type of technique isthat the apparatus becomes large in scale and complex. In addition, theweight average molecular weight of the PAS obtained by the method ofPatent Document 5 is low. Therefore, in order to create a product of thePAS obtained by this method, further polymerization must be performed,and thus the equipment becomes complex. In addition, this method is alsoinsufficient with regard to reducing the time of the polymerizationreaction.

The present invention was arrived at in light of the abovementionedissues, and an object thereof is to provide a production method that canbe used to easily obtain in a short amount of time a high molecularweight polyarylene sulfide (PAS).

Solution to Problem

In order to solve the abovementioned problems, a method for producingpolyarylene sulfide (PAS) (hereinafter, also referred to as “the presentproduction method”) according to one embodiment of the present inventionincludes: a supplying step of supplying reaction raw materials to atleast one of a plurality of reaction vessels mutually communicatedthrough a gas phase; a polymerizing step of carrying out apolymerization reaction using the plurality of reaction vessels; and adehydrating step of removing at least some of the water present in theplurality of reaction vessels; wherein each of the steps is carried outin parallel, and a reaction mixture is transferred sequentially betweenthe reaction vessels; an internal temperature of at least one reactionvessel to which the reaction raw materials are supplied is from 180° C.to 300° C.; the reaction raw materials include an organic polar solvent,a sulfur source, and a dihalo aromatic compound; and the total amount ofwater contained in the reaction raw materials that are supplied in thesupplying step is 3 moles or more per mole of the sulfur source.

Advantageous Effects of Invention

According to one aspect of the present invention, a production methodthat makes it possible to easily obtain high molecular weight PAS in ashort amount of time can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial cross-sectional view of a PAS continuous productionapparatus according to a first embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of a PAS continuous productionapparatus according to a second embodiment of the present invention.

FIG. 3 is a partial cross-sectional view of a PAS continuous productionapparatus according to a third embodiment of the present invention.

FIG. 4 is an image schematically illustrating a configuration of a PAScontinuous production apparatus according to a fifth embodiment of thepresent invention.

re supplied is from 180° C. to 300° C.

DESCRIPTION OF EMBODIMENTS

First Embodiment

Hereinafter, an embodiment of the present invention will be described.

Apparatus for Continuous Production of Polyarylene Sulfide

First, the configuration of a polyarylene sulfide (PAS) continuousproduction apparatus that can be used with respect to the method forproducing PAS according to an embodiment of the present invention(hereinafter, also referred to as “the present production method”) isdescribed based on FIG. 1.

FIG. 1 is a partial cross-sectional view illustrating a configuration ofa PAS continuous production apparatus that can be used with respect tothe PAS production method according to the present embodiment.

When described with reference to FIG. 1, a PAS continuous productionapparatus 100 is provided with a housing chamber 2 for housing aplurality of reaction vessels 1 a, 1 b, and 1 c. In the PAS continuousproduction apparatus 100, the housing chamber 2 is installed at anincline so as to form an angle θ with respect to a horizontal plane Hillustrated in FIG. 1. The shape of the housing chamber 2 is notparticularly limited, and examples include a hollow cylindrical shape ora hollow prismatic shape for which a side wall 3 a contacting thereaction vessel 1 a and a side wall 3 b contacting the reaction vessel 1c are used as bottom surfaces.

Lines for supplying each of the reaction raw materials are connected tothe side wall 3 a of the housing chamber 2. More specifically, anorganic polar solvent supply line 4 for supplying an organic polarsolvent to the housing chamber 2, a sulfur source supply line 5 forsupplying to the housing chamber 2 at least one type of sulfur sourceselected from the group consisting of alkali metal sulfides, alkalimetal hydrosulfides and hydrogen sulfide, and a dihalo aromatic compoundsupply line 6 for supplying a dihalo aromatic compound to the housingchamber 2 are respectively connected to the side wall 3 a of the housingchamber 2. Note that as necessary, an alkali metal hydroxide supply line(not illustrated) for supplying an alkali metal hydroxide to the housingchamber 2 or a water supply line (not illustrated) for supplying waterto the housing chamber 2 may be connected to the side wall 3 a.

The reaction raw materials including the organic polar solvent, thesulfur source, and the dihalo aromatic compound, and other optionallyused reaction raw materials may be respectively supplied through the gasphase to a liquid phase of the reaction vessel 1 a, or may be supplieddirectly to the liquid phase of the reaction vessel 1 a. Note that inthe present specification, the term reaction raw materials refers to rawmaterials that are used in the polymerization reaction of the PASproduction method.

A reaction mixture recovery line 7 for recovering the reaction mixturefrom the housing chamber 2 is connected to the side wall 3 b of thehousing chamber 2.

The reaction vessel 1 a and the reaction vessel 1 b are partitioned by apartition wall 8 a, and the reaction vessel 1 b and the reaction vessel1 c are partitioned by a partition wall 8 b. The reaction vessels 1 a, 1b, and 1 c are mutually communicated through the gas phase in thehousing chamber 2. As a result, the pressure of the gas phase in thehousing chamber 2 becomes uniform. Note that the effect obtained throughthis type of mutual communication is described later.

The housing chamber 2 is installed at an incline so as to form an angleθ with respect to the horizontal plane H illustrated in FIG. 1, andtherefore the maximum liquid surface level of liquid that can be storedis highest in the order of the reaction vessel 1 a, the reaction vessel1 b, and the reaction vessel 1 c. The reaction vessels 1 a, 1 b, and 1 care connected in series in the abovementioned order. The effect obtainedthrough this type of connection is described later. Note that withrespect to each reaction vessel with the exception of the furthestupstream reaction vessel 1 a in the transfer direction of the reactionmixture, a minimum height of the upstream side partition wall in thetransfer direction is higher than the maximum liquid surface level ofthat reaction vessel. That is, with respect to the reaction vessel 1 b,the minimum height of the upstream side partition wall 8 a in thetransfer direction is greater than the maximum liquid surface level ofthe reaction vessel 1 b, and with respect to the reaction vessel 1 c,the minimum height of the upstream side partition wall 8 b in thetransfer direction is greater than the maximum liquid surface level ofthe reaction vessel 1 c. Through this, reverse flow from the reactionvessel 1 b to the reaction vessel 1 a, and reverse flow from thereaction vessel 1 c to the reaction vessel 1 b are prevented. Thereaction vessels 1 a, 1 b, and 1 c respectively accommodate reactionmixtures 9 a, 9 b, and 9 c.

The reaction vessels 1 a to 1 c are connected in series in theabovementioned order, and thereby the reaction mixtures are transferredin accordance with the difference in liquid surface levels and gravity.Therefore, according to the present embodiment, there is no need toprovide a separate means for transferring a reaction mixture to the nextreaction vessel.

In the housing chamber 2, a stirring blade 10 a for stirring thereaction mixture 9 a in the reaction vessel 1 a, a stirring blade 10 bfor stirring the reaction mixture 9 b in the reaction vessel 1 b, and astirring blade 10 c for stirring the reaction mixture 9 c in thereaction vessel 1 c are installed on the same stirring shaft 11. Thestirring shaft 11 is installed so as to pierce through the side wall 3 afrom outside the housing chamber 2 and extend to reach the side wall 3b. A rotational driving device 12 for rotating the stirring shaft 11 isinstalled at the end of the stirring shaft 11 on the side wall 3 a side.

One end of an exhaust line 13 is connected near the side wall 3 a of thehousing chamber 2. A dehydration unit 14 for removing water from the gasphase in the housing chamber 2 is connected to the other end of theexhaust line 13. The dehydration unit 14 communicates with the gas phasein the housing chamber 2 through the exhaust line 13. One end of anorganic polar solvent recovery line 15 is connected to one end (forexample, a bottom part) of the dehydration unit 14. One end of a steamrecovery line 16 is connected to the other end (for example, a top part)of the dehydration unit 14. A gas-liquid separation unit 17 is connectedto the other end of the steam recovery line 16. A reaction raw materialseparation and recovery unit 19 is connected to the other end of a gasrecovery line 18 that is branched from one end (for example, a top part)of the gas-liquid separation unit 17. A waste gas line 20 and a reactionraw material resupply line 21 branch from the reaction raw materialseparation and recovery unit 19, and a reaction raw material resupplyunit 22 for resupplying at least a portion of the reaction raw materialsseparated and recovered by the reaction raw material separation andrecovery unit 19 to at least some of the reaction vessels 1 a to 1 c isconnected to the reaction raw material resupply line 21. Meanwhile, areaction raw material separation and recovery unit 24 is connected tothe other end of a liquid recovery line 23 that is branched from theother end (for example, a bottom part) of the gas-liquid separation unit17. A wastewater line 25 and a reaction raw material resupply line 26branch from the reaction raw material separation and recovery unit 24,and a reaction raw material resupply unit 27 for resupplying at least aportion of the reaction raw materials separated and recovered by thereaction raw material separation and recovery unit 24 to at least someof the reaction vessels 1 a to 1 c is connected to the reaction rawmaterial resupply line 26. At least a portion of the reaction rawmaterials may be supplied to the liquid phase of at least some of thereaction vessels 1 a to 1 c through the gas phase, or may be supplieddirectly to the liquid phase of at least some of the reaction vessels 1a to 1 c.

A gas feeding unit 28 that communicates with the gas phase in thehousing chamber 2 to feed an inert gas to the gas phase from adownstream side to an upstream side in the transfer direction of thereaction mixture, namely, from the reaction vessel 1 c towards thereaction vessel 1 a, is connected through a gas feeding line 29 to theside wall 3 b of the housing chamber 2. The inert gas is notparticularly limited, and examples include argon and other noble gases;nitrogen, and the like.

Also, a heater or other such temperature control device (notillustrated) can be connected to a wall surface of the housing chamber 2to regulate the internal temperature of the reaction vessels. Thetemperature control device does not necessarily have to be integratedwith the reaction vessels, and a plurality of temperature controldevices can regulate the temperature of a single reaction vessel, orconversely, the temperature of a plurality of reaction vessels can beregulated with a single temperature control device.

Next, the PAS production method according to the present embodiment isdescribed along with a description of the operation of the PAScontinuous production apparatus based on FIG. 1.

PAS Production Method

The present production method includes: a step of supplying reaction rawmaterials to at least one of a plurality of reaction vessels mutuallycommunicated through a gas phase; a polymerizing step of carrying out apolymerization reaction using the plurality of reaction vessels; and adehydrating step of removing at least some of the water present in theplurality of reaction vessels. These steps are carried out in parallel,and a reaction mixture is transferred sequentially between the reactionvessels. In at least one of the reaction vessels to which the reactionraw materials are supplied, the total amount of water contained in thevarious reaction raw materials such as the organic polar solvent, thesulfur source, and the dihalo aromatic compound that are supplied asreaction raw materials is 3 moles or more per one mole of the sulfursource, and the internal temperature of at least one reaction vessel towhich the reaction raw materials are supplied is from 180° C. to 300° C.

When the present production method is specifically described, in thesupplying step, each of the reaction raw materials including the organicpolar solvent, the at least one type of sulfur source selected from thegroup consisting of alkali metal sulfides, alkali metal hydrosulfidesand hydrogen sulfide, and the dihalo aromatic compound is supplied tothe housing chamber 2 through the organic polar solvent supply line 4,the sulfur source supply line 5, and the dihalo aromatic compound supplyline 6, respectively. Note that a portion or all of the reaction rawmaterials may be premixed and then supplied to the housing chamber 2.For example, a mixture of the organic polar solvent and the dihaloaromatic compound, or a mixture of the organic polar solvent and thesulfur source may be prepared in advance, and this mixture may then besupplied to the housing chamber 2. In addition, the mixture may besupplied after being heated, or may be heated, reacted, and thensupplied, or may be reacted without heating and then supplied. In thiscase, for example, in place of the organic polar solvent supply line 4and the dihalo aromatic compound supply line 6, a mixture supply line(not illustrated) can be connected to the side wall 3 a, and the mixturecan then be supplied to the housing chamber 2 through this mixturesupply line. In addition, the mixture may be supplied to at least one ofthe plurality of reaction vessels, and for example, a portion of thereaction raw materials may be supplied to not only the reaction vessel 1a, but also to another reaction vessel such as the reaction vessel 1 b.

With the present production method, the total amount of water containedin the organic polar solvent, the sulfur source, and the dihalo aromaticcompound that are supplied as reaction raw materials and in the otherreaction raw materials that are optionally used is from 3 moles to 50moles, preferably from 4 moles to 40 moles, and more preferably from 5moles to 30 moles per mole of the sulfur source. This water contentamount is measured by gas chromatography.

The internal temperature of at least one reaction vessel to which thereaction raw materials are supplied may be from 180° C. to 300° C., butthe internal temperature of the reaction vessel thereof is preferablyfrom 180° C. to 270° C., and more preferably from 180° C. to 230° C. Thedehydrating step and the reaction steps that are carried out in parallelcan be stably progressed and concluded in a short amount of time bysetting the internal temperature of at least one reaction vessel, towhich the reaction raw materials are supplied, to within theabovementioned range.

In the present embodiment, the internal temperature of the reactionvessel 1 a is preferably from 110 to 230° C., more preferably from 140to 220° C., and even more preferably from 150 to 210° C. In the presentembodiment, the internal temperature of an adjacent reaction vessel thatis adjacent to the reaction vessel 1 a, namely the reaction vessel 1 bin the present embodiment, is preferably from 170 to 260° C., morepreferably from 180 to 250° C., and even more preferably from 190 to240° C. In the present embodiment, the difference in internaltemperatures between mutually adjacent reaction vessels is preferably 2°C. or greater, more preferably 3° C. or greater, and even morepreferably 5° C. or greater. Furthermore, the internal temperature of atleast one reaction vessel to which the reaction raw materials aresupplied may be from 180° C. to 300° C.

As the at least one reaction vessel to which the reaction raw materialsare supplied, for a case of an aspect in which the reaction vessel 1 ais used as the supply reaction vessel, the internal temperature of thereaction vessel 1 a is preferably from 180 to 300° C., more preferablyfrom 180 to 270° C., and even more preferably from 180 to 230° C. Inaddition, the internal temperature of the adjacent reaction vessel thatis adjacent to this supply reaction vessel, namely the reaction vessel 1b, is preferably from 182 to 300° C., more preferably from 190 to 280°C., and even more preferably from 200 to 270° C. Furthermore, theinternal temperature of the reaction vessel 1 c, which is a reactionvessel that is adjacent to the reaction vessel 1 b, is preferably from184 to 300° C., more preferably from 190 to 290° C., and even morepreferably from 200 to 280° C. The dehydrating step and the reactionsteps that are carried out in parallel can be stably progressed andconcluded in a short amount of time by setting the internal temperatureof the reaction vessel 1 a to which the reaction raw materials aresupplied, to within the abovementioned range. Note that in the presentembodiment, some of the reaction raw materials may be supplied throughthe corresponding supply lines (not illustrated) to the reaction vessel1 b, or the reaction vessel 1 c, or to both the reaction vessels 1 b and1 c.

In the polymerizing step, the supplied organic polar solvent, sulfursource, and dihalo aromatic compound, and the other reaction rawmaterials that are optionally used are first mixed in the reactionvessel 1 a, a polymerization reaction between the sulfur source and thedihalo aromatic compound is carried out in the organic polar solvent,and thereby the reaction mixture 9 a is formed.

Those materials that are ordinarily used in the production of PAS can beused as the organic polar solvent, the at least one type of sulfursource selected from the group consisting of alkali metal sulfides,alkali metal hydrosulfides, and hydrogen sulfide, and the dihaloaromatic compound.

Examples of the organic polar solvent include organic amide solvents.Examples of the organic amide solvents include amide compounds, such asN,N-dimethylformamide and N,N-dimethylacetamide; N-alkylcaprolactamcompounds, such as N-methyl-ε-caprolactam; N-alkylpyrrolidone compoundsor N-cycloalkylpyrrolidone compounds, such as N-methyl-2-pyrrolidone(NMP) and N-cyclohexyl-2-pyrrolidone; N,N-dialkylimidazolidinonecompounds, such as 1,3-dialkyl-2-imidazolidinone; tetraalkyl ureacompounds, such as tetramethyl urea; and hexaalkylphosphate triamidecompounds, such as hexamethyl phosphate triamide.

Examples of the sulfur source include alkali metal sulfides, alkalimetal hydrosulfides, and hydrogen sulfide. The sulfur source ispreferably an alkali metal sulfide or an alkali metal hydrosulfidebecause such sulfur sources are inexpensive and easy to handle. Thesulfur source can be used, for example, in a state of an aqueous slurryor an aqueous solution, and is preferably in the state of an aqueoussolution from the perspectives of handling ease such as weighing easeand transporting ease.

Examples of alkali metal sulfides include lithium sulfide, sodiumsulfide, potassium sulfide, rubidium sulfide, and cesium sulfide.

Examples of alkali metal hydrosulfides include lithium hydrosulfide,sodium hydrosulfide, potassium hydrosulfide, rubidium hydrosulfide, andcesium hydrosulfide.

When an alkali metal hydrosulfide or hydrogen sulfide is used as thesulfur source, an alkali metal hydroxide is used in combination.Examples of the alkali metal hydroxide include lithium hydroxide, sodiumhydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide,and mixtures of two or more of these. Of these, sodium hydroxide andlithium hydroxide are preferred from the perspective of being availableat a low cost for industrial purposes. Moreover, from perspectives suchas handling ease, the alkali metal hydroxide is preferably in the formof an aqueous solution or slurry.

When any of the alkali metal sulfides, alkali metal hydrosulfides, andhydrogen sulfide are mixed and used, naturally, the mixture of thesewill be the sulfur source.

Specific examples of the dihalo aromatic compounds includeo-dihalobenzene, m-dihalobenzene, p-dihalobenzene, dihalotoluene,dihalonaphthalene, methoxy-dihalobenzene, dihalobiphenyl, dihalobenzoicacid, dihalodiphenyl ether, dihalodiphenyl sulfone, dihalodiphenylsulfoxide, and dihalodiphenyl ketone. The halogen atom in a dihaloaromatic compound indicates each atom of fluorine, chlorine, bromine,and iodine. Two halogen atoms in the dihalo aromatic compound may be thesame or different. Of these, p-dihalobenzene, m-dihalobenzene or amixture of these two is preferred, p-dihalobenzene is more preferred,and p-dichlorobenzene (pDCB) is particularly preferred.

Each of the alkali metal sulfide, alkali metal hydrosulfide, and dihaloaromatic compound may be used alone or may be used by mixing two or moretypes as long as the combination can produce PAS.

Note that, for example, for a case in which the amount of watercontained in the reaction raw materials supplied to the housing chamber2 is relatively small, water may be added to at least one of thereaction vessels 1 a to 1 c in order to facilitate the polymerizationreaction. The amount of water that may be added at that time is notparticularly limited, and for example, can be around 0.1 to 10 moles permole of the sulfur source.

PAS having a weight average molecular weight (Mw) measured through gelpermeation chromatography (GPC) of 2000 or greater, preferably 5000 orgreater, and particularly preferably 6000 or greater, and also 300000 orless, and preferably 100000 or less can be ultimately obtained bycarrying out the polymerization reaction at a temperature of from 170 to290° C. until the conversion ratio of the dihalo aromatic compoundbecomes 50% or greater.

The dihalo aromatic compound conversion ratio is preferably from 50 to100%, more preferably from 60 to 98%, even more preferably from 65 to97%, and particularly preferably from 70 to 96%. The conversion ratio ofthe dihalo aromatic compound can be calculated by determining throughgas chromatography the amount of the dihalo aromatic compound remainingin the reaction mixture and then performing a calculation based on theremaining amount of the dihalo aromatic compound, the charged amount ofthe dihalo aromatic compound, and the charged amount of the sulfursource.

A step of producing and recovering a prepolymer in the polymerizationreaction, and further increasing the weight average molecular weight ofthis prepolymer may be further included.

The weight average molecular weight of the prepolymer is 2000 orgreater, preferably 5000 or greater, and particularly preferably 6000 orgreater, and is 10000 or less, and preferably 9000 or less.

The conversion ratio of the dihalo aromatic compound when producing theprepolymer is preferably from 50 to 100%, more preferably from 60 to98%, even more preferably from 65 to 97%, and particularly preferablyfrom 70 to 96%.

In the dehydrating step of the present production method, at least aportion of the water inside the housing chamber 2 is removed from thehousing chamber 2 through the gas phase in the housing chamber 2according to the action (details are described below) of the dehydrationunit 14 through the exhaust line 13. Through this, at least a portion ofthe water present in the reaction vessels 1 a to 1 c is removed. Thewater inside the housing chamber 2 includes, for example, water suppliedto the housing chamber 2, and water produced by the polymerizationreaction. Here, water supplied to the housing chamber 2 indicates, forexample, water that has been proactively supplied to the housing chamber2, and for a case in which water is not proactively supplied to thehousing chamber 2, water supplied to the housing chamber 2 indicateswater that is ordinarily supplied along with the reaction raw materialsto the housing chamber 2 in a state of being contained in the reactionraw materials. Water has a high vapor pressure, and therefore when alarge amount of moisture is contained in the gas phase of the housingchamber 2, the inside of the housing chamber 2 can easily become a highpressure state. Because of this, pressure resistance of the housingchamber 2 becomes necessary, thereby making it difficult to achieveresource savings and a reduction in equipment costs. However, resourcesavings and a reduction in equipment costs can be effectively realizedby carrying out dehydration through the dehydration unit 14 to reducethe pressure inside the housing chamber 2. The pressure inside thehousing chamber 2, which is the reaction system, is, for example,preferably from 0.01 MPa to 0.8 MPa, more preferably from 0.05 MPa to0.6 MPa, and even more preferably from 0.1 MPa to 0.4 MPa.

As described above, the reaction vessels 1 a to 1 c are mutuallycommunicated through the gas phase in the housing chamber 2, and thepressure of the gas phase in the housing chamber 2 is uniform. Becauseof this, in the dehydrating step, water is equivalently removed from anyof the reaction vessels 1 a to 1 c by the dehydration unit 14.Therefore, the amount of water in the reaction mixture decreases movingfrom the reaction vessel 1 a to the reaction vessel 1 c, or in otherwords, moving from the upstream side to the downstream side in thetransfer direction of the reaction mixture. As a result, hindering ofthe reaction by water is suppressed, and the polymerization reaction isfacilitated. In addition, the boiling point of the reaction mixtureincreases, and therefore polymerization at high temperatures becomespossible, and the polymerization reaction can be further facilitated.Furthermore, through the above-described facilitation of thepolymerization reaction, the temperature of the reaction mixture easilyincreases, and the polymerization reaction is more easily facilitated.

As described above, with the PAS continuous production apparatus 100,for example, each unit is disposed as described above, and through theoverall matter of carrying out a continuous reaction, the temperaturesof the reaction vessels 1 a to 1 c can be increased moving from theupstream side to the downstream side in the transfer direction. In otherwords, the reaction vessels 1 a to 1 c are provided so that the internaltemperature of the reaction vessels 1 a to 1 b becomes higher movingfrom the upstream side to the downstream side in the transfer directionof the reaction mixture.

Moreover, as described above, the reaction vessels 1 a to 1 c areconnected in decreasing order from the highest maximum liquid surfacelevel of liquid that can be accommodated by each of the reactionvessels. Through this, in a step of transferring the reaction mixture,the reaction mixture can be sequentially transferred using thedifference in heights of the maximum liquid surface level. Morespecifically, when the reaction mixture 9 a and the reaction mixture 9 bexceed the maximum liquid surface levels, the reaction mixtures thereofcan pass over the partition walls 8 a and 8 b, respectively. The shapesof the partition walls 8 a and 8 b are not particularly limited, and maybe any optional shape as long as the mutual communication of thereaction vessels 1 a, 1 b, and 1 c through the gas phase in the housingchamber 2 is not hindered. In addition, the partition walls 8 a and 8 bmay also be configured with an opening part such as a through opening orslit (neither is illustrated) for example provided in the partition wallso that the reaction solution is transferred through this opening part.

In the present embodiment, an inert gas is preferably fed by the gasfeeding unit 28 to the gas phase in the housing chamber 2 from adownstream side to an upstream side in the transfer direction of thereaction mixture, namely, from the reaction vessel 1 c towards thereaction vessel 1 a. As described above, in order to maintain the statein which the amount of water in the reaction mixture decreases movingfrom the upstream side to the downstream side in the transfer directionof the reaction mixture, preferably, the configuration is such thatmoisture evaporated from the reaction mixture does not flow to theabovementioned downstream side and condense above the reaction mixture.The matter of water vapor flowing to the downstream side and condensingabove the reaction mixture can be effectively prevented by feeding theinert gas to the abovementioned gas phase in the manner described aboveusing the gas feeding unit 28.

The flow rate of the inert gas is not particularly limited as long as itis within a range that inhibits the flow of water vapor to thedownstream side. For example, for a case in which the housing chamber 2is a hollow cylindrical shape which has an inner radius r and uses theside wall 3 a and the side wall 3 b as the bottom surface, when the flowrate of the inert gas is represented by u, and the volumetric flow rateof the inert gas is represented by F, then the flow rate of the inertgas is expressed by u=F/(πr²). Here, if the water vapor does not easilyflow to the downstream side, Taylor dispersion holds true. That is, whenconsideration is given to the change from molecular diffusion dominationto convection diffusion domination, the inequality equation r·u»D(wherein, D is the diffusion coefficient of water vapor) holds true as acondition for Taylor dispersion to hold true. From the above, the flowrate of the inert gas is a value that is within a range such that, forexample, F»D·πr, more specifically, F>10D·πr, preferably F>25D·πr, andmore preferably F>50D·πr hold true. Note that for a case in which thehousing chamber 2 is a hollow columnar shape for which the side wall 3 aand the side wall 3 b are used as the bottom surface, and the verticalcross section in the transfer direction of the reaction mixture is anyoptional shape, a representative length in the vertical direction in thetransfer direction of the reaction mixture, for example, the equivalentcircular radius of the cross-section, which is any optional shape, isused as r, and can be applied in the abovementioned equation.

The stirring shaft 11 is rotated by the rotational driving device 12,and in association therewith, the stirring blades 10 a to 10 c installedon the stirring shaft 11 rotate around the stirring shaft 11, and stirthe reaction mixtures 9 a to 9 c. The stirring blades 10 a to 10 c areinstalled on the same stirring shaft 11. Therefore, all of the stirringblades 10 a to 10 c rotate with the same conditions by merely rotatingthe stirring shaft 11 by the rotational driving device 12, and thushomogeneous stirring can be realized with high efficiency.

As the abovementioned polymerization reaction advances, NaCl and otheralkali metal halides are deposited and accumulated in the reactionvessels 1 a to 1 c. As a result, for example, the volume that iseffective for advancing sufficient polymerization reactions in thereaction vessels 1 a to 1 c is reduced, and decreases in productivityand the like easily occur. Therefore, excessive maintenance operationsto remove the accumulated alkali metal halides must be performed.However, by stirring the reaction mixtures 9 a to 9 c through thestirring blades 10 a to 10 c, the alkali metal halides are easilydispersed in the reaction mixtures 9 a to 9 c, transferred to theabovementioned downstream side, and discharged to outside the housingchamber 2. On the other hand, if the stirring is too intense, thereaction mixture flows over the partition wall 8 a and/or the partitionwall 8 b, and is unnecessarily and easily mixed into a downstream sidereaction vessel from an upstream side reaction vessel.

Preferably, the stirring blade shape, quantity, rotational speed, andthe like are adjusted, as appropriate, so that dispersion of alkalimetal halides can be facilitated, and unnecessary mixing of reactionmixtures between the reaction vessels 1 a to 1 c can be avoided. Ofthese, the rotational speed of the stirring blades is, for example, setas a condition so that the alkali metal halides do not precipitate, andmore specifically, the rotational speed is set so that the stirringspeed by the stirring blades is at or above the particle floating limitstirring speed. Note that from the perspective of easily preventing thereaction mixture from flowing over the partition wall 8 a and/or thepartition wall 8 b, the upper limit of the tip speed of a stirring bladeis preferably a speed such that the rotational speed of the stirringblades becomes 60 rpm or less and more preferably 20.5 rpm or less.Moreover, the rotational paths and the like of the stirring blades arealso preferably adjusted, as appropriate, so that stirring issufficiently performed. For example, preferably, the stirring bladespass through at least a portion which is deeper than an average depth ofeach of the reaction vessels 1 a to 1 c. In particular, preferably,stirring is sufficiently implemented in the vicinity of the deepestparts of each of the reaction vessels 1 a to 1 c, and the sizes of thegap between the stirring blade 10 a and the bottom part of the reactionvessel 1 a, the gap between the stirring blade 10 a and the partitionwall 8 a, the gap between the stirring blade 10 b and the bottom part ofthe reaction vessel 1 b, the gap between the stirring blade 10 b and thepartition wall 8 b, the gap between the stirring blade 10 c and thebottom part of the reaction vessel 1 c, and the gap between the stirringblade 10 c and the side wall 3 b are made small so that alkali metalhalides do not accumulate.

Exhaust from the housing chamber 2 is supplied through the exhaust line13 to the dehydration unit 14. The dehydration unit 14 acts, forexample, as a distillation column, and a liquid having an organic polarsolvent as the main component is recovered from one end (the lower partfor example), and steam containing the sulfur source, the dihaloaromatic compound, and water is recovered from the other end (the upperpart for example).

The organic polar solvent recovered from the dehydration unit 14 may besubjected, as appropriate, to refining, etc., and then once againsupplied to the housing chamber 2 as a reaction raw material for thepolymerization reaction. At that time, supply to the housing chamber 2of the recovered organic polar solvent may be performed through theorganic polar solvent supply line 4, or may be performed through anorganic polar solvent supply line other than the organic polar solventsupply line 4. The supply destination of the recovered organic polarsolvent may be any one of the reaction vessels 1 a to 1 c, or may be acombination of two or more thereof.

The steam recovered from the abovementioned other end of the dehydrationunit 14 is supplied through the steam recovery line 16 to the gas-liquidseparation unit 17. The gas-liquid separation unit 17 acts, for example,as a distillation column, and a gas containing the sulfur source isrecovered from one end (the upper part for example), and a liquidcontaining the dihalo aromatic compound and water is recovered from theother end (the lower part for example).

The gas recovered from the one end of the gas-liquid separation unit 17is supplied through the gas recovery line 18 to the reaction rawmaterial separation and recovery unit 19. The sulfur source is separatedand recovered from the gas at the reaction raw material separation andrecovery unit 19, and is sent through the reaction raw material resupplyunit 22 to the reaction raw material resupply line 21. Meanwhile, theremaining gas is discarded as waste gas through the waste gas line 20.

At least a portion of the sulfur source separated and recovered by thereaction raw material separation and recovery unit 19 is resupplied toat least one of the reaction vessels 1 a to 1 c by the reaction rawmaterial resupply unit 22. At that time, resupply to the reaction vessel1 a of the separated and recovered sulfur source may be performedthrough the sulfur source supply line 5, or may be performed through asulfur source supply line other than the sulfur source supply line 5.Through resupply of at least a portion of the sulfur source, the sulfursource can be effectively used, and resource savings can be achieved.

The liquid recovered from the gas-liquid separation unit 17 is suppliedthrough the liquid recovery line 23 to the reaction raw materialseparation and recovery unit 24. The dihalo aromatic compound isseparated and recovered from the liquid at the reaction raw materialseparation and recovery unit 24, and is sent through the reaction rawmaterial resupply unit 27 to the reaction raw material resupply line 26.Meanwhile, the remaining liquid is discarded as wastewater through thewastewater line 25.

Therefore, at least a portion of the dihalo aromatic compound separatedand recovered by the reaction raw material separation and recovery unit24 is resupplied to at least one of the reaction vessels 1 a to 1 c bythe reaction raw material resupply unit 27. At that time, resupply tothe reaction vessel 1 a of the separated and recovered dihalo aromaticcompound may be performed through the dihalo aromatic compound supplyline 6, or may be performed through a dihalo aromatic compound supplyline other than the dihalo aromatic compound supply line 6. Throughresupply of at least a portion of the dihalo aromatic compound, thedihalo aromatic compound can be effectively used, and resource savingscan be achieved.

In addition, gravitational force is used for matters such astransferring the reaction mixture based on the height differences of themaximum liquid surface levels, and therefore a significant amount ofenergy is not required to drive the PAS continuous production apparatus100. Hence, the PAS continuous production apparatus 100 can easilyenable resource savings, energy savings, and reductions in equipmentcosts, etc.

According to the present production method, reaction raw materials needonly be supplied to at least one of a plurality of reaction vessels, andtherefore the production of PAS is simplified. In addition, the totalamount of water contained in the various reaction raw materials that aresupplied at this time is 3 moles or more per mole of the sulfur source.Therefore, treatments such as adjusting the water content amount of eachof the reaction raw materials are not necessary in the production ofPAS.

The present embodiment may further include a step of increasing theweight average molecular weight of the PAS that is obtained after thepolymerization reaction. Increasing the weight average molecular weightof the PAS can be carried out, for example, by using a polymerizationaid in the polymerization reaction. Specific examples of this type ofpolymerization aid include organic metal carboxylates, organic metalsulfonates, lithium halides, alkali metal salts of sulfuric acid,alkaline earth metal oxides, alkali metal phosphates, and alkaline earthmetal phosphates. These can be used alone or two or more types can besimultaneously used. Of these, organic metal carboxylates or lithiumhalides are preferably used. More specific examples include lithiumacetate, sodium acetate, potassium acetate, sodium propionate, lithiumbenzoate, sodium benzoate, sodium phenylacetate, sodium p-toluate andlithium chloride. Of these, lithium acetate or sodium acetate ispreferably used, and sodium acetate is more preferably used from theperspective of procurement ease at a low price.

These polymerization aids may be used alone or may be used by mixing twoor more types as long as the combination can produce the PAS.

In the present embodiment, when the total amount of water contained inthe various reaction raw materials is considered to be 100 mass %, theamount of water contained in the above-described supply reaction vessel,that is, in the reaction vessel 1 a, is preferably from 5 mass % to 99mass %, more preferably from 6 mass % to 90 mass %, and even morepreferably from 7 mass % to 80 mass %. The amount of water contained inthe supply reaction vessel is preferably within this range because whenwithin such range, the amount of water that is removed in thepolymerizing step is reduced.

In addition, the amount of water contained in the adjacent reactionvessel that is adjacent to the supply reaction vessel on the downstreamside, that is, in the reaction vessel 1 b, is preferably from 5 mass %to 50 mass %, more preferably from 6 mass % to 40 mass %, and even morepreferably from 7 mass % to 30 mass %. The amount of water contained inthe adjacent reaction vessel is preferably within this range becausewhen within such range, the amount of water that is removed in thepolymerizing step is reduced.

Note that in the present embodiment, a PAS production method that uses aspecific apparatus was described, but the production method according tothe present invention may further include other steps as long as: theproduction method includes at least a supplying step of supplyingreaction raw materials to at least one of a plurality of reactionvessels mutually communicated through a gas phase, a polymerizing stepof carrying out a polymerization reaction using the plurality ofreaction vessels, and a dehydrating step of removing at least some ofthe water present in the reaction vessels; these various steps arecarried out in parallel, and the reaction mixture is transferredsequentially between the reaction vessels; in at least one of thereaction vessels to which the reaction raw materials are supplied, thetotal water content amount of the various reaction raw materials such asthe organic polar solvent, the sulfur source, and the dihalo aromaticcompound is 3 moles or greater per mole of the sulfur source; and theinternal temperature of at least one of the reaction vessels to whichthe reaction raw materials are supplied is from 180° C. to 300° C.

In addition, reaction vessels of a specific shape were used in thepresent embodiment, but the shape of the reaction vessels is notparticularly limited.

Furthermore, the number of reaction vessels in the present embodiment isnot particularly limited. Also, the reaction vessels do not necessarilyhave to be connected in series as illustrated in FIG. 1. Therefore, forexample, some of the plurality of reaction vessels may be aligned inparallel.

Furthermore, in the present embodiment, the above-described feeding stepis preferably performed in parallel with the various above-describedsteps. In addition, the above-described separating and recovering stepand resupplying step are preferably carried out in parallel with theabove-described steps.

Moreover, in the present embodiment, a configuration in which thereaction raw materials are supplied to the reaction vessel 1 a wasdescribed, but the reaction vessel to which the reaction raw materialsare supplied is not specified.

Second Embodiment

Next, another embodiment of the present invention will be described indetail.

FIG. 2 is a partial cross-sectional view illustrating another PAScontinuous production apparatus that can be used with respect to thepresent production method. Hereinafter, the configuration and action ofthe PAS continuous production apparatus according to the presentembodiment is described based on FIG. 2. Note that members having thesame function as members described in the first embodiment are assignedthe same reference signs, and descriptions thereof are omitted.

In the present embodiment, a PAS continuous production apparatus 200used with respect to the present production method is the same as thePAS continuous production apparatus 100 of the first embodiment with theexception that the housing chamber 2 is installed horizontally, thedimensions of the partition wall 8 a and the dimensions of the partitionwall 8 b differ, and the connection position of the reaction mixturerecovery line 7 in the side wall 3 b differs.

As illustrated by FIG. 2, if the bottom surface areas of the reactionvessels 1 a to 1 c are the same, the PAS continuous production apparatus200 operates in the same manner as the PAS continuous productionapparatus 100 (see FIG. 1) presented in the first embodiment with theexception that the amount of reaction mixture that can be accommodatedis reduced in order of the reaction vessels 1 a, 1 b, and 1 c.

With the PAS continuous production apparatus 200, unlike the PAScontinuous production apparatus 100, the depth of each of the reactionvessels 1 a to 1 c is nearly constant according to the location. Hence,alkali metal halides produced by the polymerization reaction easilyaccumulate on the overall bottom surfaces of the reaction vessels 1 a to1 c, and therefore sufficient stirring by the stirring blades 10 a to 10c is particularly preferable. In order to sufficiently perform stirringby the stirring blades 10 a to 10 c so that alkali metal halides are notdeposited, the width of the stirring blades 10 a to 10 c is preferablywide, and for example, is 50% or more, preferably 60% or more, morepreferably 70% or more, and even more preferably 80% or more of thewidth of the reaction vessels 1 a to 1 c. In addition, all or some ofthe stirring blades 10 a to 10 c are preferably positioned at the centerof each reaction vessel from perspectives such as not easily generatinga large deviation in the stirring.

With respect to the present invention, cases in which the stirring shaft11 is a single shaft were presented in the abovementioned first andsecond embodiments, but the stirring shaft 11 may be multiple shafts oftwo or more shafts.

Third Embodiment

Next, yet another embodiment of the present invention will be describedin detail.

FIG. 3 is a partial cross-sectional view illustrating another PAScontinuous production apparatus that can be used with respect to thepresent production method. Hereinafter, the configuration and action ofthe present embodiment is described based on FIG. 3.

When described with reference to FIG. 3, a PAS continuous productionapparatus 300 differs from the above-described embodiments in that asegregation means for segregating the reaction vessels in the housingchamber 2 is a dividing plate having a rotating center, rather than apartition wall.

In the present embodiment, the reaction vessel 1 a and the reactionvessel 1 b are partitioned by a dividing plate 30 a, and the reactionvessel 1 b and the reaction vessel 1 c are partitioned by a dividingplate 30 b. The reaction vessels 1 a, 1 b, and 1 c are mutuallycommunicated through the gas phase in the housing chamber 2.

Moreover, a stirring blade 10 a for stirring the reaction mixture 9 a inthe reaction vessel 1 a is attached to one surface of the dividing plate30 a. Likewise, a stirring blade 10 b for stirring the reaction mixture9 b in the reaction vessel 1 b is attached to one surface of thedividing plate 30 b. Note that the stirring blades 10 a and 10 b in thepresent embodiment have a configuration in which an opening is providedat the interior side.

The stirring blades 10 a and 10 b and the dividing plates 30 a and 30 bare all installed on the same rotating shaft 31. The rotating shaft 31is installed so as to pierce through the side wall 3 a from outside thehousing chamber 2 and extend to reach the side wall 3 b. A rotationaldriving device 12 for rotating the rotating shaft 31 is installed at theend of the rotating shaft 31 on the side wall 3 a side.

Note that the stirring blades can be installed at any optional positionwith respect to the dividing plates. A dividing plate may be located atthe upstream side of a stirring blade, may be at the downstream side, ora mixture of both may be present. The dividing plate may be separatedfrom the stirring blade, but the dividing plate can be fixed andreinforced by tightly affixing and connecting the dividing plate and thestirring blade as illustrated by FIG. 3, and thus such a configurationis preferable. Moreover, the stirring blade and the dividing plate donot necessarily have to be a pair, and a location where a stirring bladeis not present between adjacent stirring blades may exist. Theprogression of the polymerization reaction can be aided, and solids inthe reaction mixture can be more smoothly transferred by providing atleast one stirring blade. Alternatively, a stirring blade does not needto be provided, and through this, a simpler apparatus configuration ismade possible.

The shape of the dividing plate is not particularly limited, and may beany optional shape that has a rotating center, and provides a clearanceof a prescribed width or an opening part so that adjacent reactionvessels are in communication while the vertical cross-section inside thehousing chamber 2 is partially blocked. For example, for a case in whichthe housing chamber 2 is a hollow cylindrical shape, as illustrated inFIG. 3, the dividing plate may be a disk-shaped dividing plate having aradius which is slightly smaller than the internal space of the housingchamber. Note that the shape of the dividing plate is not limited tothis, and may be a cage-shaped rotating article not having a centershaft.

The number of dividing plates provided on the rotating shaft may be anoptional number of one or more according to factors such as the size ofthe housing chamber and the polymerization reaction type.

For cases in which two or more dividing plates are provided, these maybe the same shape, or respectively different shapes.

Moreover, the position of each dividing plate is not particularlylimited, and each dividing plate can be provided at an optionalposition.

The shape of the stirring blade is also not particularly limited, andthe stirring blade is provided on the same shaft as that of the dividingplate, and may be any optional shape for stirring the reaction mixture.As illustrated in FIG. 3, the stirring blades 10 a, 10 b may be attachedto one of either of the surfaces of the dividing plates 30 a, 30 b, ormay be attached to both surfaces. Alternatively, the stirring blades 10a, 10 b may be attached on the rotating shaft 31 separate from thedividing plates 30 a, 30 b.

The reaction vessels 1 a to 1 c are mutually communicated through theliquid phase part thereof. As a result, the raw materials and solventsupplied to the reaction vessel 1 a are moved sequentially as a reactionmixture to the reaction vessel 1 b and the reaction vessel 1 c whilepolymerization reaction advances.

The reaction vessels 1 a to 1 c are mutually communicated through thegas phase part thereof. As a result, the pressure of the gas phase inthe housing chamber 2 becomes uniform. Furthermore, the evaporationcomponents generated during polymerization inside each reaction vesselare sequentially moved through this gas phase part in a direction fromthe reaction vessel 1 c to the reaction vessel 1 b and the reactionvessel 1 a by the temperature difference, etc. inside the apparatus, andare discharged from the exhaust line 13.

With the PAS continuous production apparatus 300 of the presentembodiment, a clearance of a prescribed width is present between aninner wall of the housing chamber 2, and the respective outer edges ofthe dividing plates 30 a, 30 b. Through this, the gas phase parts ofadjacent reaction vessels are communicated, and the liquid phase partsof adjacent reaction vessels are communicated, and as a result, thereaction mixture and a gas containing the evaporation components aremoved. Note that instead of providing a clearance, an opening part suchas a through hole or a slit for example can be provided in the dividingplate, and the reaction vessels may be communicated through the openingpart. Alternatively, both a clearance and an opening part may beprovided. Or, the dividing plate may be a mesh shape having a pluralityof fine through holes.

The width of the clearance or the size of the opening part is notparticularly limited, and can be set, as appropriate, according to theshape of the container, the shape and quantity of dividing plates, andthe like.

Fourth Embodiment

Next, yet another embodiment of the present invention will be describedin detail.

The PAS continuous production apparatus according to the presentembodiment has a plurality of reaction vessels disposed adjacent in thevertical direction inside the housing chamber. Mutually adjacentreaction vessels (not illustrated) are partitioned by a dividing platethat is fixed without a gap, and are configured so that the reactionmixture moves sequentially through a connection pipe from the upperreaction vessel to the lower reaction vessel. In addition, the gas phaseparts of each of the reaction vessels are mutually communicated througha communication pipe. Therefore, the pressure of the gas phase of eachof the reaction vessels in the housing chamber 2 is nearly the same. Thecommunication pipe that communicates the gas phase parts may be the sameas the connection pipe through which the reaction mixture sequentiallymoves, or may be a pipe that is provided separately from the connectionpipe. Here, the present embodiment is described in detail using, as anexample, a case in which a first reaction vessel and a second reactionvessel are provided in order from the top side in the verticaldirection. The first reaction vessel and the second reaction vessel arecommunicated through a first connection pipe, and a pipe wall of thefirst connection pipe projects to the first reaction vessel side. Theheight of the pipe wall of the first connection pipe is established soas to be equal to the maximum liquid surface level of liquid that can beaccommodated by the first reaction vessel. The first connection pipepierces through a first dividing plate that partitions the firstreaction vessel and the second reaction vessel.

With the PAS continuous production apparatus configured in this manner,when the height of the reaction mixture exceeds the maximum liquidsurface level of the first reaction vessel, the reaction mixture flowsover the pipe wall of the first connection pipe and into the firstconnection pipe, passes through the first connection pipe, and flowsinto the second reaction vessel. As a configuration of this type of PAScontinuous production apparatus, the reaction mixture may also besequentially moved.

In addition, the first reaction vessel and the second reaction vesselare configured so that the gas phase part of the first reaction vesseland the gas phase part of the second reaction vessel are mutuallycommunicated through a connection pipe or a communication pipe.

Fifth Embodiment

Next, yet another embodiment of the present invention will be describedin detail.

FIG. 4 is an image schematically illustrating a modified example of aconfiguration of the PAS continuous production apparatus.

When described with reference to FIG. 4, a PAS continuous productionapparatus 400 is provided with a first reaction vessel 50, a secondreaction vessel 51, and a third reaction vessel 52. The second reactionvessel 51 is disposed vertically lower than the first reaction vessel50, and the third reaction vessel 52 is disposed vertically lower thanthe second reaction vessel 51.

The first reaction vessel 50 and the second reaction vessel 51 areconnected through a first pipe 65. In addition, the second reactionvessel 51 and the third reaction vessel 52 are connected through asecond pipe 67.

The first pipe 65 is provided so that when the reaction mixture (notillustrated) in the first reaction vessel 50 exceeds the maximum liquidsurface level, the reaction mixture passes through the first pipe 65 andmoves to the second reaction vessel 51. In addition, the second pipe 67is provided so that when the reaction mixture (not illustrated) in thesecond reaction vessel 51 exceeds the maximum liquid surface level, thereaction mixture passes through the second pipe 67 and moves to thethird reaction vessel 52.

Furthermore, a ventilation unit 70 is connected to each of the first tothird reaction vessels 50 to 52. The first to third reaction vessels 50to 52 are communicated through the gas phase through the ventilationunit 70.

Through this type of configuration of the PAS continuous productionapparatus 400, the same effect as that of the above-describedembodiments 1 and 2 is obtained even when the height difference in therespective maximum liquid surface levels of the first reaction vessel 50and the second reaction vessel 51 is used to sequentially transfer thereaction mixture. Furthermore, according to the PAS continuousproduction apparatus 400, there is no need to provide a partition walllike that presented with the first and second embodiments, or a dividingplate like that presented with the third embodiment.

The PAS continuous production apparatuses of the second to fifthembodiments are configured differently than the PAS continuousproduction apparatus of the first embodiment, but all of the embodimentsare common in that gas phase parts of each of the reaction vessels arecommunicated. Therefore, dehydration is carried out by the sameconfiguration as that of the PAS continuous production apparatus of thefirst embodiment. Accordingly, similar to the case in which the PAScontinuous production apparatus of the first embodiment is used, thewater content amount of the reaction mixture can be adjusted, and thereaction raw materials can be supplied to a reaction vessel having aninternal temperature of from 180° C. to 300° C.

Summary

As described above, a method for producing polyarylene sulfide (PAS)according to one embodiment of the present invention includes: asupplying step of supplying reaction raw materials to at least one of aplurality of reaction vessels mutually communicated through a gas phase;a polymerizing step of carrying out a polymerization reaction using theplurality of reaction vessels; and a dehydrating step of removing atleast some of the water present in the plurality of reaction vessels;wherein each of the steps is carried out in parallel, and a reactionmixture is transferred sequentially between the reaction vessels; aninternal temperature of at least one reaction vessel to which thereaction raw materials are supplied is from 180° C. to 300° C.; thereaction raw materials include an organic polar solvent, a sulfursource, and a dihalo aromatic compound; and the total amount of watercontained in the reaction raw materials that are supplied in thesupplying step is 3 moles or more per mole of the sulfur source.

In one embodiment of the present production method, at least some of theplurality of reaction vessels may be connected in series.

In one embodiment of the present production method, the plurality ofreaction vessels is connected in decreasing order from a highest maximumliquid surface level of liquid that can be accommodated in each reactionvessel, and a height difference in the maximum liquid surface levels maybe used to sequentially transfer the reaction mixture.

In one embodiment of the present production method, the supplying step,the polymerizing step, the reaction mixture transferring step, and thedehydrating step may be carried out in parallel.

In one embodiment of the present production method, a feeding step offeeding an inert gas from a downstream side towards an upstream side inthe direction of transfer of the reaction mixture may be carried out inparallel with each of the steps.

In one embodiment of the present production method, a separating andrecovering step for separating and recovering some of the reaction rawmaterials, and a resupplying step for supplying at least some of thereaction raw materials to at least one of the reaction vessels may becarried out in parallel with each of the above-described steps.

In one embodiment of the present production method, the reaction vesselsmay be provided so that the internal temperature of the reaction vesselsbecomes higher moving from an upstream side to a downstream side in thetransfer direction of the reaction mixture.

In one embodiment of the present production method, the pressure in thereaction system is preferably from 0.01 MPa to 0.8 MPa.

In one embodiment of the present production method, a step of increasingthe weight average molecular weight of the polyarylene sulfide that isobtained after the polymerizing step may be further included.

In one embodiment of the present production method, the total amount ofwater contained in the organic polar solvent, the sulfur source, and thedihalo aromatic compound that are supplied as reaction raw materials inthe supplying step is 3 moles or more per mole of the sulfur source.

Embodiments of the present invention will be described in further detailhereinafter using examples. The present invention is of course notlimited to the examples below, and it goes without saying that variousaspects are possible with regard to the details thereof. Furthermore,the present invention is not limited to the embodiments described above,and various modifications are possible within the scope indicated in theclaims. Embodiments obtained by appropriately combining the technicalmeans disclosed by the embodiments are also included in the technicalscope of the present invention. In addition, all of the documentsdisclosed in the present specification are hereby incorporated byreference.

EXAMPLES Example 1

Embodiments of the present invention are described in even greaterdetail with reference once again to FIG. 1.

A PAS continuous production apparatus that was the same as the apparatusillustrated by FIG. 1 with the exception of having six reaction vesselsformed by dividing the housing chamber 2 by five partition walls wasused. This PAS continuous production apparatus was a reaction apparatusmade of titanium with semicircular partition walls and dimensions of adiameter of 100 mm diameter×a length of 300 mm. The PAS continuousproduction apparatus was charged with 950 g of NMP, after which atemperature 1 of a portion delimited by a first partition wall and asecond partition wall from the upstream side was maintained at 230° C.,and a temperature 2 of a portion delimited by a third partition wall anda fourth partition wall was maintained at 260° C., and a metering pumpwas used to continuously supply from each supply line the raw materialsincluding a liquid mixture of NMP and p-dichlorobenzene (pDCB) at a flowrate of 3.53 g/min (NMP:pDCB (weight ratio)=988:268), and 36.00 wt. %NaSH at a flow rate of 0.84 g/min.

At the same time, a distillation device connected to the PAS continuousproduction apparatus was used, and water was continuously removed fromthe PAS continuous production apparatus while controlling the pressureto a gage pressure of 0.32 MPa using a pressure regulation valve. Inaddition, the pDCB in the water that was removed was separated with asettling tank and returned to the PAS continuous production apparatus.

Furthermore, gas from the distillation device was washed with 1.37 g/minof 15.84 wt. % NaOH and 0.50 g/min of NMP supplied to a gas absorptioncolumn, and the gas was then released. At that time, the total amount ofthe NMP and NaOH aqueous solution that had absorbed gas was supplied tothe reaction vessel of the upstream side of the first partition wallfrom the upstream side. Through this, the water (total amount of watercontained in the various reaction raw materials) supplied to thereaction vessel of the upstream side of the first partition wall fromthe upstream side was 17.4 moles per mole of the sulfur source. Thepolymerization reaction product was continuously overflowed anddischarged from the reaction apparatus, and cooled. At this time, theaverage residence time of the polymerization reaction product in thereaction apparatus was approximately 3 hours.

After the above operations were continued for 5 hours, the water contentamount of the reaction mixture in a reaction vessel delimited by thefirst partition wall and the second partition wall from the upstreamside was measured, and was found to be 0.7 moles per mole of the rawmaterial sulfur source. Moreover, when the reaction mixture that hadoverflowed from the reaction apparatus at that time was analyzed, theconversion ratio of the raw material pDCB was 97.0%. The reactionmixture was washed and filtered three times with acetone of the sameweight, and three times with water, the obtained cake was dried at 80°C. for 8 hours in a vacuum, and a PPS powder was obtained. The weightaverage molecular weight Mw obtained through GPC of this PPS powder was27300.

In addition, the internal temperature of the reaction vessel at theupstream side of the first partition wall from the upstream side, namelythe reaction vessel to which reaction raw materials are supplied, waschanged in a range of from 190 to 210° C. for the five hours in whichthe operations were continued.

Example 2

A continuous production apparatus that was the same as the apparatusillustrated by FIG. 3 with the exception of having eleven reactionvessels formed by dividing the housing chamber body by ten disk-shapeddividing plates was used. With this continuous production apparatus, thehousing chamber body had dimensions of an inner diameter of 108 mm by alength of 300 mm. All of the ten dividing plates had the same shape, andwere provided on a rotating shaft having a diameter of 5 mm. Twoanchor-type stirring blades of the same material as the downstream sidedividing plate were provided in a cross shape at the upstream sidesurface of each of the dividing plates in the transfer direction of thereaction mixture. The diameter of the dividing plate was 100 mm, thelength of the anchor-type stirring blade in the longitudinal axialdirection was 90 mm, and the length in the short axial direction was 40mm. At a position where a dividing plate was provided, the percentageoccupied by the cross-sectional area of the clearance with respect tothe vertical cross-section of the internal space of the housing chamberwas approximately 14%.

The abovementioned continuous production apparatus was charged with 1700g of N-methyl-2-pyrrolidone (NMP) as an organic amide solvent, afterwhich nitrogen gas was flowed from the downstream side of the eleventhreaction vessel counted from the upstream side in the transfer directionof the reaction mixture, and while the nitrogen gas was being flowed, anexternal heater installed at the bottom portion of the housing chamberwas used to maintain a temperature 1 of the second reaction vesselcounted from the upstream side at 220° C., a temperature 2 of the fifthreaction vessel at 240° C., and a temperature 3 of the eleventh reactionvessel at 260° C. Here, the flow rate of the nitrogen gas was 0.1NL/min, and in a standard state, the linear velocity of the nitrogen gaspassing through the clearance of the dividing plate 0.8 cm/s.

A metering pump was used to continuously supply, from each supply line,raw materials including an NMP-pDCB liquid mixture at a flow rate of3.92 g/min (NMP:pDCB (weight ratio)=1799:1093), and 37.4 wt. % NaSH at aflow rate of 1.47 g/min.

At the same time, a distillation device connected to the continuousproduction apparatus was used, and water was continuously removed fromthe continuous production apparatus while controlling the pressure to agage pressure of 0.32 MPa using a pressure regulation valve. Inaddition, the pDCB in the water that was removed was separated with asettling tank and returned to the continuous production apparatus. Inaddition, gas from the distillation device was washed with 2.38 g/min of16.93 wt. % NaOH and 0.50 g/min of NMP supplied to a gas absorptioncolumn, and the gas was then released. At that time, the total amount ofthe NMP and NaOH aqueous solution that had absorbed gas was supplied tothe first reaction vessel from the upstream side.

The water (total amount of water contained in the various reaction rawmaterials) supplied to the first reaction vessel counted from theupstream side was 16.4 moles per mole of the sulfur source. Thepolymerization reaction product was continuously overflowed anddischarged from the reaction apparatus, and cooled. At this time, theaverage residence time of the polymerization reaction product in thereaction apparatus was approximately 4 hours.

After the above operations were continued for 6 hours, the reactionmixture that had overflowed from the reaction apparatus was analyzed,and the conversion ratio of the raw material pDCB was 93.8%. Thereaction mixture was washed and filtered three times with acetone of thesame weight, and three times with water, the obtained cake was dried at80° C. for 8 hours in a vacuum, and a PPS powder was obtained. In termsof polystyrene, the weight average molecular weight Mw obtained throughGPC of this PPS powder was 10400.

In addition, the internal temperature of the reaction vessel at theupstream side of the first dividing plate from the upstream side, namelythe reaction vessel to which reaction raw materials are supplied, waschanged in a range of from 190 to 220° C. for the six hours in which theoperations were continued.

The following is clear from each of the above examples. The time forproducing a high polymer PAS can be easily reduced by setting the totalamount of water contained in the various reaction raw materials such asthe organic polar solvent, the sulfur source, and the dihalo aromaticcompound in at least one of the reaction vessels to which the reactionraw materials are supplied to 3 moles or more per one mole of the sulfursource, and setting the internal temperature of the reaction vessel towhich the reaction raw materials are supplied to a temperature of from180° C. to 300° C.

REFERENCE SIGNS LIST

-   1 a, 1 b, 1 c: Reaction vessel-   2: Housing chamber-   3A, 3 b: Side wall-   4: Organic polar solvent supply line-   5: Sulfur source supply line-   6: Dihalo aromatic compound supply line-   7: Reaction mixture recovery line-   8 a, 8 b: Partition wall-   9 a, 9 b, 9 c: Reaction mixture-   10 a, 10 b, 10 c: Stirring blade-   11: Stirring shaft-   12: Rotational driving device-   13: Exhaust line-   14: Dehydration unit-   15: Organic polar solvent recovery line-   16: Vapor recovery line-   17: Gas-liquid separation unit-   18: Gas recovery line-   19, 24: Reaction raw material separation and recovery unit-   20: Waste gas line-   21, 26: Reaction raw material resupply line-   22, 27: Reaction raw material resupply unit-   23: Liquid recovery line-   25: Wastewater line-   28: Gas feeding unit-   29: Gas feeding line-   30 a, 30 b: Dividing plate-   31: Rotating shaft-   100, 200, 300, 400: PAS continuous production apparatus-   H: Horizontal plane

The invention claimed is:
 1. A method for producing polyarylene sulfide, the method comprising: a supplying step of supplying reaction raw materials to at least one of a plurality of reaction vessels mutually communicated through a gas phase; a polymerizing step of carrying out a polymerization reaction using the plurality of reaction vessels; and a dehydrating step of removing at least some of the water present in the plurality of reaction vessels; wherein each of the steps is carried out in parallel, and a reaction mixture is transferred sequentially between the reaction vessels; an internal temperature of at least one reaction vessel to which the reaction raw materials are supplied is from 180° C. to 300° C.; the reaction raw materials include an organic polar solvent, a sulfur source, and a dihalo aromatic compound; and the total amount of water contained in the reaction raw materials that are supplied in the supplying step is 3 moles or more per mole of the sulfur source, wherein the reaction vessels are separated by dividing plates or partition walls, or the reaction vessels are connected in the decreasing order from a highest maximum liquid surface level of liquid that can be accommodated in each reaction vessel, and a height difference in the maximum liquid surface levels is used to sequentially transfer the reaction mixture.
 2. The polyarylene sulfide production method according to claim 1, wherein at least some of the plurality of reaction vessels are connected in series.
 3. The polyarylene sulfide production method according to claim 1, wherein the supplying step, the polymerizing step, the reaction mixture transferring step, and the dehydrating step are carried out in parallel.
 4. The polyarylene sulfide production method according to claim 1, wherein a feeding step of feeding an inert gas from a downstream side towards an upstream side in a direction of transfer of the reaction mixture is carried out in parallel with each of the steps.
 5. The polyarylene sulfide production method according to claim 1, wherein a separating and recovering step of separating and recovering some of the reaction raw materials, and a resupplying step of supplying at least a portion of the raw materials to at least one of the reaction vessels are carried out in parallel with each of the steps.
 6. The polyarylene sulfide production method according to claim 1, wherein the reaction vessels are provided so that an internal temperature of the reaction vessels becomes higher moving from an upstream side to a downstream side in the transfer direction of the reaction mixture.
 7. The polyarylene sulfide production method according to claim 1, wherein the pressure in the reaction system is from 0.01 MPa to 0.8 MPa.
 8. The polyarylene sulfide production method according to claim 1, further comprising a step of increasing the weight average molecular weight of the polyarylene sulfide that is obtained after the polymerizing step.
 9. The polyarylene sulfide production method according to claim 1, wherein when the total amount of water contained in the organic polar solvent, the sulfur source, and the dihalo aromatic compound that are supplied as reaction raw materials in the supplying step is 3 moles or more per mole of the sulfur source. 